Question

PLEASE PLEASE HELP

Answer 1

Answer:

8.51×10^-3 cm

Step-by-step explanation:

Hope this helps :)

Answer 2

Answer:

$8.51x10^{-3}cm$

Step-by-step explanation:

In order to add or subtract numbers in scientific notation, the powers of ten must have the same exponent.  In this caes the diameter of an average human body cell is a power of -4 and the diameter of a plant cell is a power of -3.  In order to add them, we can move the decimal over for the body cell diameter:

$5.1x10^{-4}=0.51x10^{-3}$

Add the two values: $0.51x10^{-3}+8x10^{-3}=8.51x10^{-3}cm$